Mobile communication has greatly changed people's life, but people's pursuit of mobile communication of higher performance never stops. To cope with an explosive mobile data traffic growth, massive device connections, and continuous emergence of various new services and application scenarios in future, the fifth generation (5G) mobile communications system emerges. As a part of 5G, Internet of Things has a rapidly increasing market demand. A forecast shows that by the year 2022, a quantity of connections to 5G Internet of Things will reach 18 billion.
Currently, in a 3GPP (3rd Generation Partnership Project) standard, a new air interface technology is designed to bear an IoT (Internet of Things) service based on a cellular network. This type of IoT is referred to as CIoT. For example, with development of 3GPP, CIoT based on an LTE cellular network emerges. However, the LTE cellular network is mainly oriented to users of voice and a large data volume, and intends to support an application scenario in which a user moves at a high speed, and improve a throughput of a cell and user experience as much as possible. However, in contrast to features and requirements of the IoT of low rate, low mobility, low costs, and low power consumption, the LTE (Long Term Evolution) cellular network has an excessively redundant and complex protocol stack structure, and signaling interaction between protocol layers is excessively frequent. Consequently, a terminal device has a complex structure, and costs are relatively high. Therefore, a protocol architecture of the LTE cellular network needs to be optimized and improved, to meet a future CIoT service bearer requirement.